How to check if a module exist

Hi!I'm programming in VBA. What I want to do is, to call a module, but only if it already exists. Is there any possibillity to check in vba if a module (Eg. "module1) exists in my project (eg. project1)?

Actually i also would be interested in the same for shapefiles. Any possibility to check if a shapefile does already exist? any ideas?